A U.S. district judge on Friday issued a preliminary injunction requiring Nexstar and Tegna to remain separate, despite closing their $6.2 billion megamerger last month. Why it matters: The ruling significantly dampens the consolidation outlook for the entire local broadcast industry. Zoom in: In a lengthy decision, District Judge Troy Nunley said the court agrees with DirecTV that the merger would force national pay-TV providers like DirecTV to lift their prices on consumers, causing "irreparable harm." He also said the plaintiffs' argument that the deal will reduce competition in dozens of markets was likely to prevail in court. Between the lines: The preliminary injunction follows Nunley's decision to grant a temporary restraining order last month. Nexstar said it will appeal the ruling. Catch up quick: Nexstar, the country's largest broadcast group, announced a deal to acquire Tegna for $6.2 billion last year.…